Magnetic Loop Antenna for SOTA chasing 12 October 2013
During the week I made a home-brew HF Magnetic Loop antenna for chasing SOTA activators. Today I get to try it out!
The main loop is 3/8 inch copper pipe 1 metre in diameter and mounted 1.5 metres above the ground. The inner loop (temporary) is 2 mm copper wire formed to make a 200 mm diameter loop. The inner loop will be replaced with a copper pipe loop of the same diameter, it’s now ready to mount. The tuning range of the loop is 7 MHz to 22 MHz.
The tuning capacitor is an E.F. Johnson dual gang 200 pf per section. Additional capacitance is required to tune 40m, I have used a 63 pf doorknob capacitor to switch across the main tuning capacitor. Tuning is very narrow with the standard tuning knob. I have a 5:1 vernier dial and a shaft insulator to add to the capacitor rotor, but for now is works well.
Today I chased 3 SOTA stations using a Yaesu FT-817, 5 watts output into the Magnetic Loop antenna. Signal reports were:
Josh VK2JOS on VK2/HU-054, report 5-7 and 5-6
Andrew VK2FAJG on VK2/ST-001, report 5-6 and 3-4
Glenn VK3YY on VK3/VT-022 5-5 and 5-5
Glenn VK3YY on VK3/VT-013, 5-4 and 5-5
Glenn VK3YY on VK3/VT-016, 5-5 and 5-2
I could hear Mark VK3PI, just wasn’t quick enough to call him, I was busy making a 40m/20m link dipole for the VK1 loan SOTA kit.
I could not hear Ed VK2JI on Mount Elliot.
Very happy with the home-brew Magnetic Loop and the noise reduction.
For later updates see: